So, I got a reply back from Raytec late last night and regarding telemetry inputs on their units (I assume this goes for any of their hardware that has the telemetry feature):
Telemetry is a “volt free” contact. Telemetry operates as Open / Closed circuit.
I'm still trying to digest that but I think it sounds like, in a nutshell, I would only need to close a circuit (aka short a pair of wires?) to turn the unit on or off -- is that your take on that as well?
I may be ordering direct thru their sales people in Canada since I can't find anyone... I'll keep you posted on what I get as I'm awaiting another reply from Raytec on whether to get the i2 or i4 with the wide angle optional lens for my situation.
[edited to remove UK link]